What Is a REST API? Principles Explained Simply

REST (Representational State Transfer) is an architectural style for designing web APIs where every piece of data is modeled as a 'resource' accessed via a URL, and standard HTTP methods (GET, POST, PUT, DELETE) express the action to take on that resource.

Common causes

• REST was proposed as a way to build web APIs that leverage HTTP's existing semantics (methods, status codes, caching) instead of inventing a custom protocol on top of it

How to fix it

• Model each entity as a resource with its own URL: /users, /users/42, /users/42/orders
• Use HTTP methods to express the action instead of encoding verbs in the URL — GET /users/42 not /getUser?id=42
• Keep requests stateless — each request should carry everything the server needs (like an auth token) rather than relying on server-side session state between requests

Example

GET    /api/articles        → list articles
GET    /api/articles/42     → get one article
POST   /api/articles        → create an article
PUT    /api/articles/42     → replace an article
DELETE /api/articles/42     → delete an article

FAQ

Is REST the same as JSON?

No — REST is an architectural style independent of data format. JSON is just the most common format used in REST APIs today; REST APIs have historically also used XML.